With the increasing complexity of urban underground pipeline networks, the precise detection of closely spaced parallel pipelines has become one of the technical difficulties in the field of underground pipeline detection. Aiming at the problems such as electromagnetic interference, signal superposition and insufficient positioning and depth determination accuracy existing in the detection of parallel pipelines, the technical application of the profile method in solving these difficult problems is systematically studied. Through the theoretical analysis, method innovation and case verification, the implementation effects of key technologies such as joint inversion of horizontal and vertical magnetic fields, and profile curve fitting are discussed.